Effect of an injury prevention training program on risk factors associated with ACL injury

Abstract

Increased involvement in women's sports has been met with a disproportionate incidence of anterior cruciate ligament (ACL) injuries. The underlying cause of ACL injury is likely multi-factorial, with risk factors including deficits in lower extremity kinematics, kinetics, muscle activity, strength, stability, and sensitivity. Insight into risk factors has prompted several injury prevention programs. However, program outcomes have been mixed. Therefore, the purpose of this study was to examine the effect of specialized training on risk factors theorized to increase the incidence of ACL injury. ^ Fifty-six (28 control, 28 intervention) apparently healthy females volunteered to participate in this study. Training was conducted three times per week for a period of six weeks. Training included agility, plyometric, balance, and strength exercises. Risk factor assessment included evaluation of simultaneous single leg drop landing 3-D motion analysis, electromyography, and ground reaction force. Data collection also included knee joint proprioception, laxity, and strength testing. ^ Intervention group displayed an increase (p < 0.001) in knee flexion and a decrease (p = 0.02) in knee valgus with no change in corresponding knee moments. An increase (p < 0.001) in maximum knee flexion angle and decrease (p < 0.001) in corresponding knee moment was observed. Intervention group exhibited an increase (p < 0.001) in amplitude and delay (p < 0.001) in onset time in semi-membranosus activity. There were no significant changes observed in variability of COM excursion along the x-axis, y-axis and z-axis. Vertical ground reaction force decreased (p < 0.001) following training. The Intervention group demonstrated greater proprioceptive sensitivity at 15 degrees (p < 0.001), 30 degrees (p = 0.001), and 45 degrees ( p < 0.001). A decrease in passive drawer (p < 0.001) and maximum manual drawer (p < 0.001) knee laxity was also observed. ^ The depth of this investigation served to contribute information not previously found in ACL injury prevention program studies. The product of the current training protocol led to significant mechanical and muscular improvements in single drop landing outcomes. Future research should explore the utility of training in athletes and across a multitude of ACL injury risk factors and several high risk maneuvers.^